Resin composition, resin film, laminate, multilayer printed wiring board and method for producing multilayer printed wiring board

ABSTRACT

The present invention relates to a resin composition comprising a maleimide compound having a saturated or unsaturated divalent hydrocarbon group and a divalent group having at least two imido bonds; and a catalyst comprising at least one selected from the group consisting of an imidazole compound, a phosphorus compound, an azo compound and an organic peroxide.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national phase application filed under 35U.S.C. § 371 of International Application No. PCT/JP2017/024520, filedJul. 4, 2017, designating the United States, which claims priority fromJapanese Patent Application No. 2016-133542, filed Jul. 5, 2016, whichare hereby incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a resin composition, a resin film, alaminate, a multilayer printed wiring board, and a method for producinga multilayer printed wiring board.

BACKGROUND ART

In mobile communication devices represented by cell phones, base stationapparatuses thereof network infrastructure devices such as severs androuters, and electronic devices such as large computers, signals usedare being increased year by year in the speed and the capacity. Alongtherewith, readiness for higher frequencies becomes necessary forprinted wiring boards mounted on these electronic devices, and there aredemanded substrate materials having a low relative dielectric constantand a low dielectric loss tangent which enable the transmission loss tobe reduced. In recent years, as such applications handlinghigh-frequency signals, besides in the above-mentioned electronicdevices, also in ITS fields (automobiles, traffic system fields) andindoor short-distance communication fields, there have advanced thepractical uses and practical plans of novel systems handlinghigh-frequency radio signals; and it is supposed that hereafter,low-transmission loss substrate materials are further demanded onprinted wiring boards mounted on these devices.

Further since from recent year's environmental problems, there have beendemanded the mounting of electronic components by using a lead-freesolder, and the flame retardation by the halogen freeness, there becomenecessary a higher heat resistance and flame retardancy for materialsfor printed wiring board than hitherto.

For printed wiring boards demanding a low transmission loss, asheat-resistant thermoplastic polymers exhibiting excellenthigh-frequency characteristics, polyphenylene ether (PPE)-based resinsare conventionally used. In uses of polyphenylene ether-based resins,there are proposed, for example, methods of using a polyphenylene etherand a thermosetting resin in combination; and specifically, there aredisclosed a resin composition containing a polyphenylene ether and anepoxy resin (for example, see Patent Literature 1), a resin compositionusing a polyphenylene ether and a cyanate ester resin, which is low inthe relative dielectric constant among thermosetting resins, incombination (for example, see Patent Literature 2), and the like.

Further the present inventors propose a resin composition capable ofbeing improved in compatibility, heat resistance, thermal expansioncharacteristics, adhesiveness to conductors and the like by using apolyphenylene ether resin and a polybutadiene resin as bases and makingthe resin composition to have a semi-IPN structure in its productionstage (A-stage) (for example, see Patent Literature 3).

Further, use of maleimide compounds as a material for printed wiringboards is being studied. For example, Patent Literature 4 discloses aresin composition which has a maleimide compound having at least twomaleimide skeletons, an aromatic diamine compound having at least twoamino groups and having an aromatic ring structure, a catalyst having abasic group and a phenolic hydroxyl group promoting the reaction of themaleimide compound with the aromatic diamine compound, and a silica.

CITATION LIST Patent Literature

Patent Literature 1: JP 58-69046 A1

Patent Literature 2: JP 61-18937 A1

Patent Literature 3: JP 2008-95061 A1

Patent Literature 4: JP 2012-255059 A1

SUMMARY OF INVENTION Technical Problem

For substrate materials for printed wiring boards to be used in therecent year's high-frequency band, however, it is demanded, in additionto high-frequency characteristics and high adhesiveness to conductors,that various types of characteristics be further excellent, such as lowthermal expansion coefficient.

The present invention, in consideration of such present situation, hasan object to provide a resin composition having excellent high-frequencycharacteristics (low relative dielectric constant, low dielectric losstangent), and having also heat resistance and adhesiveness to conductorsin high levels, and a resin film, a laminate and a multilayer printedwiring board which are produced by using the resin composition. Thepresent invention also has an object to provide a method for producing amultilayer printed wiring board using the resin film.

Solution to Problem

As a result of exhaustive studies to solve the above problems, thepresent inventors have found that a resin composition comprising aspecific maleimide compound and a specific catalyst can solve the aboveproblems, and this finding has led to the completion of the presentinvention.

That is, the present invention includes the following aspects.

[1] A resin composition comprising a maleimide compound having asaturated or unsaturated divalent hydrocarbon group and a divalent grouphaving at least two imido bonds; and a catalyst comprising at least oneselected from the group consisting of an imidazole compound, aphosphorus compound, an azo compound and an organic peroxide.[2] The resin composition according to [1], wherein the catalystcomprises an organic peroxide.[3] The resin composition according to [1] or [2], wherein a one-hourhalf-life temperature of the organic peroxide is 110 to 250° C.[4] The resin composition according to any one of [1] to [3], whereinthe number of carbon atoms of the hydrocarbon group is 8 to 100.[5] The resin composition according to any one of [1] to [4], whereinthe hydrocarbon group is a group represented by the following formula(II).

In the formula (II), R₂ and R₃ each independently represent an alkylenegroup having 4 to 50 carbon atoms; R₄ represents an alkyl group having 4to 50 carbon atoms; and R₅ represents an alkyl group having 2 to 50carbon atoms.[6] A resin film made by using the resin composition according to anyone of [1] to [5].[7] A laminate comprising a resin layer comprising a cured substance ofthe resin composition according to any one of [1] to [5], and aconductor layer.[8] A multilayer printed wiring board comprising a resin layercomprising a cured substance of the resin composition according to anyone of [1] to [5], and circuit layers.[9] A method for producing a multilayer printed wiring board, comprisinga step of laminating the resin film according to [6] on an inner layercircuit board to form a resin layer, a step of heating and pressing theresin layer to cure the resin layer, and a step of forming a circuitlayer on the cured resin layer.

Advantageous Effects of Invention

The present invention can provide a resin composition having excellenthigh-frequency characteristics (low relative dielectric constant, lowdielectric loss tangent), and having also heat resistance andadhesiveness to conductors in high levels, and a resin film, a laminateand a multilayer printed wiring board which are produced by using theresin composition. Further the present invention can also provide amethod for producing a multilayer printed wiring board having excellenthigh-frequency characteristics (low relative dielectric constant, lowdielectric loss tangent) and heat resistance by using the resin film.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram illustrating a production step of amultilayer printed wiring board according to the present embodiment.

FIG. 2 is a schematic diagram illustrating a production step of an innerlayer circuit board.

FIG. 3 is a schematic diagram illustrating a production step of amultilayer printed wiring board according to the present embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, as required, by reference to the drawings, a preferredembodiment of the present invention will be described in detail.However, the present invention is not limited to the followingembodiment.

Definitions

In the present description, a “high-frequency region” refers to a regionof 300 MHz to 300 GHz, and particularly refers to 3 GHz to 300 GHz. Inthe present description, a numerical value range indicated by “to”indicates a range including numerical values described before and after“to” as the minimum value and the maximum value, respectively.

In the numerical value range described stepwise in the presentdescription, the upper limit value or the lower limit value in anumerical value range of a certain stage may be replaced by the upperlimit value or the lower limit value of another stage. In the numericalvalue range described in the present description, the upper limit valueor the lower limit value in the numerical value range may be replaced bya value indicated in Examples. “A or B” may include either one of A andB, or may include the both.

[Resin Composition]

A resin composition of the present embodiment comprises a maleimidecompound having a saturated or unsaturated divalent hydrocarbon groupand a divalent group having at least two imido bonds, and a catalystcomprising at least one selected from the group consisting of animidazole compound, a phosphorus compound, an azo compound and anorganic peroxide.

<(A) Maleimide Compound Having a Saturated or Unsaturated DivalentHydrocarbon Group and a Divalent Group Having at Least Two Imido Bonds>

A maleimide compound having a saturated or unsaturated divalenthydrocarbon group and a divalent group having at least two imido bondsaccording to the present embodiment is referred to as (A) component insome cases. The (A) component is a compound having an (a) maleimidegroup, a (b) divalent group having at least two imido bonds, and a (c)saturated or unsaturated divalent hydrocarbon group. In some cases, the(a) maleimide group is referred to as a structure (a); the (b) divalentgroup having at least two imido bonds is referred to as a structure (b);and the (c) saturated or unsaturated divalent hydrocarbon group isreferred to as a structure (c). By using the (A) component, there can beobtained a resin composition having high-frequency characteristics andhigh adhesiveness to conductors.

The (a) maleimido group is not especially limited, and is a commonmaleimido group. Although the (a) maleimide group may be bonded to anaromatic ring, or may be bonded to an aliphatic chain, from theviewpoint of dielectric characteristics, it is preferable that the (a)maleimide group be bonded to a long-chain aliphatic chain (for example,a saturated hydrocarbon group having 8 to 100 carbon atoms). By makingthe (A) component to have a structure in which the (a) maleimide groupis boded to a long-chain aliphatic chain, the high-frequencycharacteristics of the resin composition can further be improved.

The structure (b) is not especially limited, but examples thereofinclude a group represented by the following formula (I).

In the formula (I), R₁ represents a tetravalent organic group. R₁ is notespecially limited as long as being a tetravalent organic group, but forexample, from the viewpoint of the handleability, may be a hydrocarbongroup having 1 to 100 carbon atoms, may be a hydrocarbon group having 2to 50 carbon atoms, or may be a hydrocarbon group having 4 to 30 carbonatoms.

R₁ may be a substituted or nonsubstituted siloxane site. Examples of thesiloxane site include structures originated from dimethylsiloxane,methylphenylsiloxane and diphenylsiloxane.

In the case where R₁ is substituted, examples of the substituent includean alkyl group, an alkenyl group, an alkynyl group, a hydroxyl group, analkoxy group, a mercapto group, a cycloalkyl group, a substitutedcycloalkyl group, a heterocycle group, a substituted heterocycle group,an aryl group, a substituted aryl group, a heteroaryl group, asubstituted heteroaryl group, an aryloxy group, a substituted aryloxygroup, a halogen atom, a haloalkyl group, a cyano group, a nitro group,a nitroso group, an amino group, an amido group, —C(O)H,—NR_(x)C(O)—N(R_(x))₂, —OC(O)—N(R_(x))₂, an acyl group, an oxyacylgroup, a carboxyl group, a carbamate group and a sulfonamido group.Here, R_(x) represents a hydrogen atom or an alkyl group. One or two ormore of these substituents can be selected according to the purposes,the applications and the like.

As R₁, preferable is, for example, a tetravalent residue of an acidanhydride having two or more anhydride rings in one molecule thereof,that is, a tetravalent group made by eliminating two acid anhydridegroups (—C(═O)OC(═O)—) from the acid anhydride. Examples of the acidanhydride include compounds as described later.

From the viewpoint of the mechanical strength, it is preferable that R₁be aromatic, and it is more preferable that R₁ be a group made byeliminating two acid anhydride groups from pyromellitic anhydride. Thatis, it is more preferable that the structure (b) be a group representedby the following formula (III).

From the viewpoint of the flowability and the circuit embeddability, itis preferable that the structure (b) be present in plural numbers in the(A) component. In this case, the structures (b) may be identical or maybe different. It is preferable that the number of the structures (b) inthe (A) component be 2 to 40; being 2 to 20 is more preferable; andbeing 2 to 10 is still more preferable.

From the viewpoint of the dielectric characteristics, the structure (b)may be a group represented by the following formula (IV) or thefollowing formula (V).

The structure (c) is not especially limited, and may be any of linear,branched and cyclic. From the viewpoint of high-frequencycharacteristics, it is preferable that the structure (c) be an aliphatichydrocarbon group. Further the number of carbon atoms of the saturatedor unsaturated divalent hydrocarbon group may be 8 to 100, or may be 10to 70 or 15 to 50. The hydrocarbon group may have a branch. It ispreferable that the structure (c) be an alkylene group having 8 to 100carbon atoms which may have a branch; being an alkylene group having 10to 70 carbon atoms which may have a branch is more preferable; and beingan alkylene group having 15 to 50 carbon atoms which may have a branchis still more preferable. When the structure (c) is an alkylene grouphaving 8 or more carbon atoms which may have a branch, the molecularstructure is easily made to be of a three-dimensional one, and thedensity is easily lowered due to the increase in the free volume of thepolymer. That is, since a low dielectric constant can be attained, itbecomes easy for the high-frequency characteristics of the resincomposition to be improved. Further when the (A) component has thestructure (c), the flexibility of the resin composition according to thepresent embodiment is improved, and the handleability (tackiness,cracking, powder dropping and the like) and the strength of a resin filmfabricated from the resin composition can be enhanced.

Examples of the structure (c) include alkylene groups such as a nonylenegroup, a decylene group, an undecylene group, a dodecylene group, atetradecylene group, a hexadecylene group, an octadecylene group and anonadecylene group; arylene groups such as a benzylene group, aphenylene group and a naphthylene group; arylene alkylene groups such asa phenylene methylene group, a phenylene ethylene group, abenzylpropylene group, a naphthylene methylene group and a naphthyleneethylene group; and arylene dialkylene groups such as a phenylenedimethylene group and a phenylene diethylene group.

From the viewpoint of the high-frequency characteristics, thelow-thermal expansion characteristics, the adhesiveness to conductors,the heat resistance and the low hygroscopic property, as the structure(c), the group represented by the following formula (II) is especiallypreferable.

In the formula (II), R₂ and R₃ each independently represent an alkylenegroup having 4 to 50 carbon atoms. From the viewpoint of the furtherimprovement of the flexibility and the easiness of the synthesis, it ispreferable that R₂ and R₃ each independently be an alkylene group having5 to 25 carbon atoms; being an alkylene group having 6 to 10 carbonatoms is more preferable; and being an alkylene group having 7 to 10carbon atoms is still more preferable.

In the formula (II), R₄ represents an alkyl group having 4 to 50 carbonatoms. From the viewpoint of the further improvement of the flexibilityand the easiness of the synthesis, it is preferable that R₄ be an alkylgroup having 5 to 25 carbon atoms; being an alkyl group having 6 to 10carbon atoms is more preferable; and being an alkyl group having 7 to 10carbon atoms is still more preferable.

In the formula (II), R₅ represents an alkyl group having 2 to 50 carbonatoms. From the viewpoint of the further improvement of the flexibilityand the easiness of the synthesis, it is preferable that R₅ be an alkylgroup having 3 to 25 carbon atoms; being an alkyl group having 4 to 10carbon atoms is more preferable; and being an alkyl group having 5 to 8carbon atoms is still more preferable.

From the viewpoint of the flowability and the circuit embeddability, thestructures (c) may be present in plural numbers in the (A) component. Inthis case, the structures (c) may be identical or may be different. Forexample, it is preferable that 2 to 40 structures (c) be present in the(A) component; the presence of 2 to 20 structures (c) is morepreferable; and the presence of 2 to 10 structures (c) is still morepreferable.

The content of the (A) component in the resin composition is notespecially limited. From the viewpoint of the heat resistance, it ispreferable that the content of the (A) component be 2 to 98% by mass tothe total mass of the resin composition (solid content); being 10 to 50%by mass is more preferable; and being 10 to 30% by mass is still morepreferable.

The molecular weight of the (A) component is not especially limited.From the viewpoint of the handleability, the flowability and the circuitembeddability, it is preferable that the weight-average molecular weight(Mw) of the (A) component be 500 to 10000; being 1000 to 9000 is morepreferable; being 1500 to 9000 is still more preferable; being 1500 to7000 is further still more preferable; and being 1700 to 5000 isespecially preferable.

Mw of the (A) component can be measured by a gel permeationchromatography (GPC) method.

Here, the measurement condition of GPC is as follows.

Pump: L-6200 type [manufactured by Hitachi High-Technologies Corp.]

Detector: L-3300 type RI [manufactured by Hitachi High-TechnologiesCorp.]

Column oven: L-655A-52 [manufactured by Hitachi High-Technologies Corp.]

Guard column and columns: TSK Guardcolumn HHR-L+TSKgel G4000HHR+TSKgelG2000HHR [all, manufactured by Tosoh Corp., trade name]

Column size: 6.0×40 mm (guard column), 7.8×300 mm (columns)

Eluent: tetrahydrofuran

Specimen concentration: 30 mg/5 mL

Injection volume: 20 μL

Flow volume: 1.00 mL/min

Measurement temperature: 40° C.

A method for producing the (A) component is not limited. The (A)component may be fabricated, for example, by reacting an acid anhydridewith a diamine to thereby synthesize an amine-terminated compound, andthereafter reacting the amine-terminated compound with an excessiveamount of maleic anhydride.

Examples of the acid anhydride include pyromellitic anhydride, maleicanhydride, succinic anhydride, 3,3′,4,4′-benzophenonetetracarboxylicdianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride and3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride. These acidanhydrides may be used singly or in combinations of two or moreaccording to the purposes, applications and the like. Here, as describedabove, As R₁ of the above formula (I), there can be used tetravalentorganic groups originated from acid anhydrides as cited in the above.From the viewpoint of better dielectric characteristics, it ispreferable that the acid anhydride be pyromellitic anhydride.

Examples of the diamine include dimer diamines,2,2-bis(4-(4-aminophenoxy)phenyl)propane,1,3-bis(4-aminophenoxy)benzene, 4,4′-bis(4-aminophenoxy)biphenyl,4,4′-diamino-3,3′-dihydroxybiphenyl,1,3-bis[2-(4-aminophenyl)-2-propyl]benzene,1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, polyoxyalkylenediamines, and[3,4-bis(1-aminoheptyl)-6-hexyl-5-(1-octenyl)]cyclohexene. These may beused singly or in combinations of two or more according to the purposes,applications and the like.

The (A) component may be, for example, a compound represented by thefollowing formula (XIII).

In the formula, R and Q each independently represent a divalent organicgroup. As R, a group having the same structure as the above-mentionedstructure (c) can be used, and as Q, the same group as theabove-mentioned R₁ can be used. n represents an integer of 1 to 10.

As the (A) component, commercially available compounds can also be used.Examples of commercially available compounds include productsmanufactured by Designer Molecules Inc., and specifically includeBMI-1500, BMI-1700, BMI-3000, BMI-5000 and BMI-9000 (any of which is atrade name). From the viewpoint of acquiring better high-frequencycharacteristics, it is more preferable that as the (A) component,BMI-3000 be used.

<(B) Catalyst Comprising at Least One Selected from the Group Consistingof an Imidazole Compound, a Phosphorus Compound, an Azo Compound and anOrganic Peroxide>

A (B) catalyst comprising at least one selected from the groupconsisting of an imidazole compound, a phosphorus compound, an azocompound and an organic peroxide, according to the present embodiment isreferred to as (B) component in some cases. The (B) component is acatalyst to promote curing of the (A) component. By making the resincomposition of the present embodiment to contain a specific catalyst,the solder heat resistance can be improved.

Examples of the imidazole compound include methylimidazole,phenylimidazole and an isocyanate-masked imidazole. Examples of theisocyanate-masked imidazole include an addition reaction product of ahexamethylene diisocyanate resin with 2-ethyl-4-methylimidazole. Theimidazole compound is not especially limited, but from the viewpoint ofthe storage stability of the resin composition, an isocyanate-maskedimidazole is preferable.

The phosphorus compound can be used without being especially limited aslong as being a catalyst containing a phosphorus atom. Examples of thephosphorus compound include organophosphines such as triphenylphosphine,diphenyl(alkylphenyl)phosphine, tris(alkylphenyl)phosphine,tris(alkoxyphenyl)phosphine, tris(alkylalkoxyphenyl)phosphine,tris(dialkylphenyl)phosphine, tris(trialkylphenyl)phosphine,tris(tetraalkylphenyl)phosphine, tris(dialkoxyphenyl)phosphine,tris(trialkoxyphenyl)phosphine, tris(tetraalkoxyphenyl)phosphine,trialkylphosphine, dialkylarylphosphine and alkyldiarylphosphine;complexes of organophosphines and organoborons; and adducts of tertiaryphosphine with quinones. As the phosphorus compound, from the viewpointthat the curing reaction of the (A) component progresses sufficientlyand higher adhesiveness to conductors can be exhibited, the adducts oftertiary phosphine with quinones are preferable.

Examples of the azo compound include 2,2′-azobis-isobutyronitrile,2,2′-azobis-2-methylbutyronitrile,1,1′-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2′-azobisisobutyrateand 1,1′-azobis-(1-acetoxy-1-phenylethane).

Examples of the organic peroxide include dicumyl peroxide, dibenzoylperoxide, 2-butanone peroxide, tert-butyl perbenzoate, di-tert-butylperoxide, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane,bis(tert-butylperoxyisopropyl)benzene, tert-butyl hydroperoxide,di(4-methylbenzoyl) peroxide, di(3-methylbenzoyl) peroxide, dibenzoylperoxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, dilauroylperoxide, di(3,5,5-trimethylhexanoyl) peroxide and tert-butylperoxypivalate.

It is preferable that the (B) component contain an organic peroxidehaving a one-hour half-life temperature of 110 to 250° C.; containing anorganic peroxide having a one-hour half-life temperature of 115 to 250°C. is more preferable; containing an organic peroxide having a one-hourhalf-life temperature of 120 to 230° C. is still more preferable; andcontaining an organic peroxide having a one-hour half-life temperatureof 130 to 200° C. is especially preferable. When the one-hour half-lifetemperature is in this range, there can be obtained a resin compositionwhich makes the solder heat resistance good and has a high degree ofcoating freedom. From the similar viewpoint, it is preferable that theone-minute half-life temperature of the organic peroxide be 150° C. orhigher; being 160° C. or higher is more preferable; and being 170° C. orhigher is still more preferable. The upper limit value of the one-minutehalf-life temperature of the organic peroxide is not especially limited,but may be 300° C. Here, the one-hour half-life temperature and theone-minute half-life temperature refer to temperatures at whichhalf-life periods described later become one hour and one minute,respectively.

Here, the half-life period of an organic peroxide is an index toindicate the decomposition speed of the organic peroxide at a constanttemperature, and is indicated by a time required until the originalorganic peroxide decomposes and its amount of active oxygen becomes ½.The half-life period of an organic peroxide can be calculated, forexample, as follows.

First, the organic peroxide is dissolved in a solvent (for example,benzene) relatively inactive to radicals to prepare an organic peroxidesolution in a dilute concentration, which is then enclosed in a glasstube subjected to nitrogen substitution. Then, the glass tube isimmersed in a thermostatic chamber set at a predetermined temperature topyrolyze the organic peroxide. Generally, since the decomposition of anorganic peroxide in a dilute solution can be handled approximately as afirst-order reaction, the half-life period can be represented by thefollowing expressions (1) and (2) where x represents the concentrationof a decomposing organic peroxide; k, the decomposition speed constant;t, the time; and a, the initial concentration of the organic peroxide.dx/dt=k(a−x)  (1)ln a/(a−x)=kt  (2)

Further the half-life period (t_(1/2)), since being a time requireduntil the amount of the organic peroxide reduces to a half of theinitial amount, can be represented by the following expression (3).kt _(1/2)=ln 2  (3)

Therefore, the half-life period (t_(1/2)) of a certain temperature canbe determined from the expression (3) by pyrolyzing the organic peroxideat the constant temperature, plotting the relation between the time tand the ln a/(a−x) and determining k from the gradient of an obtainedstraight line.

The content of the (B) component in the resin composition is notespecially limited, but may be 0.1 to 5% by mass to the total mass ofthe resin composition. From the viewpoint of sufficiently curing the (A)component, it is preferable that the content of the (B) component be 0.1to 10 parts by mass with respect to 100 parts by mass of the (A)component; being 1 to 5 parts by mass is more preferable; and being 1.5to 5 parts by mass is still more preferable.

<(C) Aromatic Maleimide Compound>

The resin composition according to the present embodiment may comprise a(C) aromatic maleimide compound different from the (A) component. The(C) aromatic maleimide compound according to the present embodiment isreferred to as (C) component in some cases. Here, a compound capable ofcorresponding to both of the (A) component and the (C) component isdetermined to belong to the (A) component, but in the case of comprisingtwo or more kinds of compounds capable of corresponding to both of the(A) component and the (C) component, one out of them is determined tobelong to the (A) component and the others the (C) component. By usingthe (C) component, the resin composition becomes one excellentparticularly in the low thermal expansion characteristics. That is, theresin composition of the present embodiment, by using the (A) componentand the (C) component in combination, can be further improved in the lowthermal expansion characteristics and the like while retaining gooddielectric characteristics. It is presumed that the reason therefor isbecause a cured substance obtained from the resin composition containingthe (A) component and the (C) component contains a polymer having astructural unit consisting of the (A) component, which has lowdielectric characteristics, and a structural unit consisting of the (C)component, which is low in the thermal expansion.

That is, it is preferable that the (C) component has a lower thermalexpansion coefficient than the (A) component. Examples of the (C)component having a lower thermal expansion coefficient than the (A)component include maleimido group-containing compounds having a lowermolecular weight than the (A) component, maleimido group-containingcompounds having more aromatic rings than the (A) component, andmaleimido group-containing compounds having a shorter main chain thanthe (A) component.

The content of the (C) component in the resin composition is notespecially limited. From the viewpoint of the low thermal expansionproperty and the dielectric characteristics, it is preferable that thecontent of the (C) component be 1 to 95% by mass to the total mass ofthe resin composition (solid content); being 1 to 50% by mass is morepreferable; and being 1.5 to 30% by mass is still more preferable.

The blend proportion of the (A) component and the (C) component in theresin composition is not especially limited. From the viewpoint of thedielectric characteristics and the low thermal expansion coefficient, itis preferable that the mass ratio (C)/(A) of the (A) component and the(C) component be 0.01 to 3; being 0.03 to 2 is more preferable; being0.05 to 1 is still more preferable; and being 0.05 to 0.5 is especiallypreferable.

The (C) component is not especially limited as long as having anaromatic ring. Since the aromatic ring is rigid and low in the thermalexpansion, by using the (C) component having an aromatic ring, thethermal expansion coefficient of the resin composition can be reduced.Although the maleimide group may be bonded to an aromatic ring or analiphatic chain, from the viewpoint of the low thermal expansionproperty, it is preferable that the maleimide group be bonded to anaromatic ring. Further, it is also preferable that the (C) component bea polymaleimide compound containing two or more maleimido groups.

Specific examples of the (C) component include 1,2-dimaleimidoethane,1,3-dimaleimidopropane, bis(4-maleimidophenyl)methane,bis(3-ethyl-4-maleimidophenyl)methane,bis(3-ethyl-5-methyl-4-maleimidophenyl)methane, 2,7-dimaleimidofluorene,N,N′-(1,3-phenylene)bismaleimide,N,N′-(1,3-(4-methylphenylene))bismaleimide, bis(4-maleimidophenyl)sulfone, bis(4-maleimidophenyl) sulfide, bis(4-maleimidophenyl) ether,1,3-bis(3-maleimidophenoxy)benzene,1,3-bis(3-(3-maleimidophenoxy)phenoxy)benzene, bis(4-maleimidophenyl)ketone, 2,2-bis(4-(4-maleimidophenoxy)phenyl)propane,bis(4-(4-maleimidophenoxy)phenyl) sulfone,bis[4-(4-maleimidophenoxy)phenyl] sulfoxide,4,4′-bis(3-maleimidophenoxy)biphenyl,1,3-bis(2-(3-maleimidophenyl)propyl)benzene,1,3-bis(1-(4-(3-maleimidophenoxy)phenyl)-1-propyl)benzene,bis(maleimidocyclohexyl)methane,2,2-bis[4-(3-maleimidophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, andbis(maleimidophenyl)thiophene. These may be used singly or incombinations of two or more. Among these, from the viewpoint of morereducing the hygroscopic property and the thermal expansion coefficient,it is preferable to use bis(3-ethyl-5-methyl-4-maleimidophenyl)methane.From the viewpoint of further enhancing the breaking strength of a resinfilm formed from the resin composition and the metal foil peel strength,as the (C) component, it is preferable to use2,2-bis(4-(4-maleimidophenoxy)phenyl)propane.

From the viewpoint of the moldability, it is preferable that the (C)component be, for example, a compound represented by the followingformula (VI).

In the formula (VI), A₄ represents a residue represented by thefollowing formula (VII), (VIII), (IX) or (X); and A₅ represents aresidue represented by the following formula (XI). From the viewpoint ofthe low thermal expansion property, it is preferable that A₄ be aresidue represented by the following formula (VII), (VIII) or (IX).

In the formula (VII), R₁₀ each independently represent a hydrogen atom,an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogenatom.

In the formula (VIII), R₁₁ and R₁₂ each independently represent ahydrogen atom, an aliphatic hydrocarbon group having 1 to 5 carbon atomsor a halogen atom; and A₆ represents an alkylene group or an alkylidenegroup having 1 to 5 carbon atoms, an ether group, a sulfide group, asulfonyl group, a carbonyl group, a single bond or a residue representedby the following formula (VIII-1).

In the formula (VIII-1), R₁₃ and R₁₄ each independently represent ahydrogen atom, an aliphatic hydrocarbon group having 1 to 5 carbon atomsor a halogen atom; and A₇ represents an alkylene group having 1 to 5carbon atoms, an isopropylidene group, an ether group, a sulfide group,a sulfonyl group, a carbonyl group or a single bond.

In the formula (IX), i is an integer of 1 to 10.

In the formula (X), R₁₅ and R₁₆ each independently represent a hydrogenatom or an aliphatic hydrocarbon group having 1 to 5 carbon atoms; and jis an integer of 1 to 8.

In the formula (XI), R₁₇ and R₁₈ each independently represent a hydrogenatom, an aliphatic hydrocarbon group having 1 to 5 carbon atoms, analkoxy group having 1 to 5 carbon atoms, a hydroxyl group or a halogenatom; and A₈ represents an alkylene group or an alkylidene group having1 to 5 carbon atoms, an ether group, a sulfide group, a sulfonyl group,a carbonyl group, a fluorenylene group, a single bond, a residuerepresented by the following formula (XI-1) or a residue represented bythe following formula (XI-2).

In the formula (XI-1), R₁₉ and R₂₀ each independently represent ahydrogen atom, an aliphatic hydrocarbon group having 1 to 5 carbon atomsor a halogen atom; and A₉ represents an alkylene group having 1 to 5carbon atoms, an isopropylidene group, a m-phenylenediisopropylidenegroup, a p-phenylenediisopropylidene group, an ether group, a sulfidegroup, a sulfonyl group, a carbonyl group or a single bond.

In the formula (XI-2), R₂₁ each independently represent a hydrogen atom,an aliphatic hydrocarbon group having 1 to 5 carbon atoms or a halogenatom; and A₁₀ and A₁₁ each independently represent an alkylene grouphaving 1 to 5 carbon atoms, an isopropylidene group, an ether group, asulfide group, a sulfonyl group, a carbonyl group or a single bond.

It is preferable, from the viewpoint of the solubility to organicsolvents, the high-frequency characteristics and the high adhesivenessto conductors, that a polyaminobismaleimide compound is used as the (C)component. The polyaminobismaleimide compound can be obtained, forexample, by subjecting a compound having two maleimido groups onterminals thereof and an aromatic diamine compound having two primaryamino groups in the molecule to a Michael addition reaction in anorganic solvent.

The aromatic diamine compound having two primary amino groups in themolecule is not especially limited, but examples thereof include4,4′-diaminodiphenylmethane, 4,4′-diamino-3,3′-dimethyl-diphenylmethane,2,2′-dimethyl-4,4′-diaminobiphenyl,2,2-bis(4-(4-aminophenoxy)phenyl)propane,4,4′-[1,3-phenylenebis(1-methylethylidene)]bisaniline, and4,4′-[1,4-phenylenebis(1-methylethylidene)]bisaniline. These may be usedsingly or in combinations of two or more.

Further from the viewpoint of the solubility to organic solvents beinghigh, the reaction ratio in the synthesis being high, and the heatresistance being capable of being raised, 4,4′-diaminodiphenylmethaneand 4,4′-diamino-3,3′-dimethyl-diphenylmethane are preferable. These maybe used singly or in combinations of two or more according to thepurposes, applications and the like.

An organic solvent to be used when the polyaminobismaleimide compound isproduced is not especially limited, but examples thereof includealcohols such as methanol, ethanol, butanol, butyl cellosolve, ethyleneglycol monomethyl ether and propylene glycol monomethyl ether; ketonessuch as acetone, methyl ethyl ketone, methyl isobutyl ketone andcyclohexanone; aromatic hydrocarbons such as toluene, xylene andmesitylene; esters such as methoxyethyl acetate, ethoxyethyl acetate,butoxyethyl acetate and ethyl acetate; and nitrogen-containing compoundssuch as N,N-dimethylformamide, N,N-dimethylacetamide andN-methyl-2-pyrrolidone. These may be used singly or as a mixture of twoor more. Among these, methyl ethyl ketone, cyclohexanone, propyleneglycol monomethyl ether, N,N-dimethylformamide and N,N-dimethylacetamideare preferable from the viewpoint of the solubility.

<Diamine Compound>

The resin composition according to the present embodiment may furthercomprise a diamine compound. Examples of the diamine compounds include4,4′-diaminodiphenylmethane, 4,4′-diamino-3,3′-dimethyl-diphenylmethane,2,2′-dimethyl-4,4′-diaminobiphenyl,2,2-bis(4-(4-aminophenoxy)phenyl)propane,4,4′-[1,3-phenylenebis(1-methylethylidene)]bisaniline,4,4′-[1,4-phenylenebis(1-methylethylidene)]bisaniline and1,3-bis[2-(4-aminophenyl)-2-propyl]benzene. These may be used singly orin combinations of two or more.

Further from the viewpoint of the solubility to organic solvents beinghigh, the reaction ratio in the synthesis being high, and the heatresistance being capable of being raised,1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 4,4′-diaminodiphenylmethaneor 4,4′-diamino-3,3′-dimethyl-diphenylmethane is preferable. These maybe used singly or in combinations of two or more according to thepurposes, applications and the like.

<(D) Thermosetting Resin>

The resin composition of the present embodiment can further comprise a(D) thermosetting resin different from the (A) component and the (C)component. Here, compounds capable of corresponding to the (A) componentor the (C) component are determined not to belong to the (D)thermosetting resin. Examples of the (D) thermosetting resin includeepoxy resins and cyanate ester resins. When the (D) thermosetting resinis contained, the low thermal expansion characteristics and the like ofthe resin composition can further be improved.

In the case where as the (D) thermosetting resin, an epoxy resin iscontained, the epoxy resin is not especially limited. Examples ofthereof include bisphenol A epoxy resins, bisphenol F epoxy resins,bisphenol S epoxy resins, alicyclic epoxy resins, aliphatic chain epoxyresins, phenol novolac epoxy resins, cresol novolac epoxy resins,bisphenol A novolac epoxy resins, phenol aralkyl epoxy resins,naphthalene skeleton-containing epoxy resins such as naphthol novolacepoxy resins and naphthol aralkyl epoxy resins, bifunctional biphenylepoxy resins, biphenyl aralkyl epoxy resins, dicyclopentadiene epoxyresins and dihydroanthracene epoxy resins. These may be used singly orin combinations of two or more. Among these, from the viewpoint of thehigh-frequency characteristics and the thermal expansioncharacteristics, it is preferable to use a naphthaleneskeleton-containing epoxy resin or a biphenyl aralkyl epoxy resin.

In the case where as the (D) thermosetting resin, a cyanate ester resinis contained, the cyanate ester resin is not especially limited, butexamples thereof include 2,2-bis(4-cyanatophenyl)propane,bis(4-cyanatophenyl)ethane, bis(3,5-dimethyl-4-cyanatophenyl)methane,2,2-bis(4-cyanatophenyl)-1,1,1,3,3,3-hexafluoropropane,α,α′-bis(4-cyanatophenyl)-m-diisopropylbenzene, cyanate ester compoundsof phenol-added dicyclopentadiene polymers, phenol novolac cyanate estercompounds, and cresol novolac cyanate ester compounds. These may be usedsingly or in combinations of two or more. Among these, from theviewpoint of costs and from the viewpoint of high-frequencycharacteristics, it is preferable to use2,2-bis(4-cyanatophenyl)propane.

(Curing Agent)

In the case where the resin composition of the present embodimentcontains the (D) thermosetting resin, the resin composition may furthercomprise a curing agent of the (D) thermosetting resin. Thereby, areaction when a cured substance of the resin composition is obtained cansmoothly be advanced, and the physical properties of the obtained curedsubstance of the resin composition are enabled to be suitably regulated.

In the case of using an epoxy resin, a curing agent is not especiallylimited, but examples thereof include polyamine compounds such asdiethylenetriamine, triethylenetetramine, diaminodiphenylmethane,m-phenylenediamine and dicyandiamide; polyphenol compounds such asbisphenol A, phenol novolac resins, cresol novolac resins, bisphenol Anovolac resins and phenol aralkyl resins; acid anhydrides such asphthalic anhydride and pyromellitic anhydride; various carboxylic acidcompounds; and various active ester compounds.

In the case of using a cyanate ester resin, a curing agent is notespecially limited, but examples thereof include various monophenolcompounds, various polyphenol compounds, various amine compounds,various alcohol compounds, various acid anhydrides and variouscarboxylic acid compounds. These may be used singly or in combinationsof two or more.

(Inorganic Filler)

The resin composition of the present embodiment may further comprise aninorganic filler. When optional suitable inorganic fillers arecontained, there can be improved the low thermal expansioncharacteristics, the high elastic modulus property, the heat resistance,the flame retardancy and the like of the resin composition. Theinorganic filler is not especially limited, but examples thereof includesilica, alumina, titanium oxide, mica, beryllia, barium titanate,potassium titanate, strontium titanate, calcium titanate, aluminumcarbonate, magnesium hydroxide, aluminum hydroxide, aluminum silicate,calcium carbonate, calcium silicate, magnesium silicate, siliconnitride, boron nitride, calcined clay, talc, aluminum borate and siliconcarbide. These may be used singly or in combinations of two or more.

The shape and the particle diameter of the inorganic filler are notespecially limited, and the particle diameter of the inorganic fillermay be, for example, 0.01 to 20 μm or 0.1 to 10 μm. Here, the particlediameter refers to an average particle diameter, and is a particlediameter at the point corresponding to 50% in volume when a cumulativefrequency distribution curve of particle diameters is determined withthe total volume of the particles being taken to be 100%. The averageparticle diameter can be measured by a particle size distributionanalyzer using a laser diffraction scattering method, or the like.

In the case of using an inorganic filler, the use volume thereof is notespecially limited, but it is preferable, for example, that the contentratio of the inorganic filler be 3 to 75% by volume with respect to thetotal volume of the solid content in the resin composition; and being 5to 70% by volume is more preferable. In the case where the content ofthe inorganic filler in the resin composition is in the above range, itbecomes easy for better curability, moldability and chemical resistanceto be attained.

In the case of using an inorganic filler, the use amount thereof is notespecially limited, but it is preferable, for example, that the contentratio of the inorganic filler be 5 to 90% by mass with respect to thetotal volume of the solid content in the resin composition; and being 10to 80% by mass is more preferable. In the case where the content of theinorganic filler in the resin composition is in the above range, itbecomes easy for better curability, moldability and chemical resistanceto be attained.

In the case of using an inorganic filler, for the purpose of improvingthe dispersibility of the inorganic filler, the close adhesiveness toorganic components, and the like, as required, a coupling agent can beused concurrently. The coupling agent is not especially limited, andthere can be used, for example, various types of silane coupling agents,and titanate coupling agents. These may be used singly or incombinations of two or more. The amount used of the coupling agent alsois not especially limited, and may be made to be, with respect to 100parts by mass of the inorganic filler to be used, 0.1 to 5 parts by massor 0.5 to 3 parts by mass, for example. When the amount thereof used isin this range, decreases in various characteristics are small and itbecomes easy for advantages by use of the inorganic filler to beeffectively exhibited.

In the case of using a coupling agent, although the so-called integralblending system may be used in which after an inorganic filler isblended in the resin composition, the coupling agent is added, it ispreferable to use a system in which there is used an inorganic fillerpreviously surface-treated in dry or wet with the coupling agent. Byusing this method, advantages of the above inorganic filler can bedeveloped more effectively.

(Thermoplastic Resin)

The resin composition of the present embodiment, from the viewpoint ofraising the handleability of the resin film, may further comprise athermoplastic resin. The kind of the thermoplastic resin is notespecially limited, and the molecular weight also is not limited, butfrom the viewpoint of enhancing the compatibility with the (A)component, it is preferable that the number-average molecular weight(Mn) be 200 to 60000.

From the viewpoint of the film formability and the hygroscopicresistance, it is preferable that the thermoplastic resin be athermoplastic elastomer. The thermoplastic elastomer includes saturatedthermoplastic elastomers; and the saturated thermoplastic elastomersinclude chemically modified saturated thermoplastic elastomers andnon-modified saturated thermoplastic elastomers. The chemically modifiedsaturated thermoplastic elastomers include styrene-ethylene-butylenecopolymers modified with maleic anhydride. Specific examples of thechemically modified saturated thermoplastic elastomers include TuftecM1911, M1913 and M1943 (all, manufactured by Asahi Kasei Corp., tradenames). On the other hand, the non-modified saturated thermoplasticelastomers include non-modified styrene-ethylene-butylene copolymers.Specific examples of the non-modified saturated thermoplastic elastomersinclude Tuftec H1041, H1051, H1043 and H1053 (all, manufactured by AsahiKasei Corp., trade names).

From the viewpoint of the film formability, the dielectriccharacteristics and the hygroscopic resistance, it is more preferablethat the saturated thermoplastic elastomer have a styrene unit in themolecule. Here, in the present description, the “styrene unit” refers toa unit originated from a styrene monomer in a polymer; and the“saturated thermoplastic elastomer” refers to one having a structure inwhich any aliphatic hydrocarbon moieties other than aromatic hydrocarbonmoieties in the styrene unit are constituted of saturated bondinggroups.

The content of the styrene unit in the saturated thermoplastic elastomeris not especially limited, but it is preferable that the content ratiobe 10 to 80% by mass in mass percentage of the styrene unit to the totalmass of the saturated thermoplastic elastomer; and being 20 to 70% bymass is more preferable. When the content ratio of the styrene unit isin the above range, the saturated thermoplastic elastomer is likely tobe excellent in the film appearance, the heat resistance and theadhesiveness.

Specific examples of the saturated thermoplastic elastomer having thestyrene unit in the molecule include styrene-ethylene-butylenecopolymers. The styrene-ethylene-butylene copolymers can be obtained,for example, by carrying out hydrogenation on unsaturated double bondswhich structural units originated from butadiene of a styrene-butadienecopolymer have.

The content of the thermoplastic resin is not especially limited, butfrom the viewpoint of making the dielectric characteristics better, itis preferable that the content be 0.1 to 15% by mass to the total massof the solid content of the resin composition; being 0.3 to 10% by massis more preferable; and being 0.5 to 5% by mass is still morepreferable.

(Flame Retardant)

The resin composition of the present embodiment may further be blendedwith a flame retardant. The flame retardant is not especially limited,but there are suitably used bromine-based flame retardants,phosphorus-based flame retardants, metal hydroxides, and the like. Thebromine-based flame retardants include brominated epoxy resins such asbrominated bisphenol A epoxy resins and brominated phenol novolac epoxyresins; bromination addition-type flame retardants such ashexabromobenzene, pentabromotoluene, ethylenebis(pentabromophenyl),ethylenebistetrabromophthalimide,1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane, tetrabromocyclooctane,hexabromocyclododecane, bis(tribromophenoxy)ethane, brominatedpolyphenylene ethers, brominated polystyrenes and2,4,6-tris(tribromophenoxy)-1,3,5-triazine; and brominationreaction-type flame retardants containing an unsaturated double bondgroup such as tribromophenylmaleimide, tribromophenyl acrylate,tribromophenyl methacrylate, tetrabromobisphenol A dimethacrylate,pentabromobenzyl acrylate, and brominated styrene. These flameretardants may be used singly or in combinations of two or more.

The phosphorus-based flame retardants include aromatic phosphate esterssuch as triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate,cresyl diphenyl phosphate, cresyl di-2,6-xylenyl phosphate andresorcinol bis(diphenylphosphate); phosphonate esters such as divinylphenylphosphonate, diallyl phenylphosphonate and bis(1-butenyl)phenylphosphonate; phosphinate esters such as phenyldiphenylphosphinate, methyl diphenylphosphinate and9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivatives;phosphazene compounds such as bis(2-allylphenoxy)phosphazene anddicresylphosphazene; and other phosphorus-based flame retardants such asmelamine phosphate, melamine pyrophosphate, melamine polyphosphate,melam polyphosphate, ammonium polyphosphate, phosphorus-containingvinylbenzyl compounds and red phosphorus. The metal hydroxide flameretardants include magnesium hydroxide and aluminum hydroxide. Theseflame retardants may be used singly or in combinations of two or more.

The resin composition of the present embodiment can be obtained byhomogeneously dispersing and mixing the above-mentioned respectivecomponents; and its preparation means, conditions and the like are notespecially limited. Examples of the preparation means include a methodin which the respective components in predetermined amounts blended arefully and homogeneously stirred and mixed by a mixer or the like, andthereafter kneaded by using a mixing roll, an extrusion machine, akneader, a roll, an extruder, or the like; and further, the obtainedkneaded material is cooled and crushed. Here, also the kneading form isnot especially limited.

The relative dielectric constant of a cured substance of the resincomposition of the present embodiment is not especially limited, butfrom the viewpoint of being suitably used in a high-frequency band, itis preferable that the relative dielectric constant at 10 GHz be 3.6 orlower; being 3.1 or lower is more preferable; and being 3.0 or lower isstill more preferable. The lower limit of the relative dielectricconstant is not especially limited, but may be, for example, about 1.0.Further from the viewpoint of being suitably used in a high-frequencyband, it is preferable that the dielectric loss tangent of a curedsubstance of the resin composition of the present embodiment be 0.004 orlower; and being 0.003 or lower is more preferable. The lower limit ofthe relative dielectric constant is not especially limited, but may be,for example, about 0.0001. The relative dielectric constant and thedielectric loss tangent can be measured by methods shown in the belowExamples.

From the viewpoint of suppressing warpage of the laminate, it ispreferable that the thermal expansion coefficient of a cured substanceof the resin composition of the present embodiment be 10 to 90 ppm/OC;being 10 to 45 ppm/° C. is more preferable; and being 10 to 40 ppm/OC isstill more preferable. The thermal expansion coefficient can be measuredaccording to IPC-TM-650 2.4.24.

The resin composition of the present embodiment has excellent dielectriccharacteristics of being low in both the relative dielectric constantand the dielectric loss tangent in a high-frequency region. Hence, inthe case where a metal-clad cured resin film is made by laminating ametal foil (copper foil) on the surface (one surface or both surfaces)of the resin film, dielectric characteristics excellent in thehigh-frequency region can be attained.

[Resin Film]

In the present embodiment, a resin film can be produced by using theabove-mentioned resin composition. Here, the resin film refers to anuncured or semicured filmy resin composition.

A production method of the resin film is not limited, but the resin filmcan be obtained, for example, by drying a resin layer formed by applyingthe resin composition on a support base material. Specifically, theresin composition is applied on a support base material by using a kisscoater, a roll coater, a comma coater or the like, and thereafter, maybe dried in a heating dryer or the like, for example, at a temperatureof 70 to 250° C., preferably 70 to 200° C., for 1 to 30 min, preferably3 to 15 min. Thereby, there can be obtained the resin film in the statethat the resin composition is semicured.

Here, the resin film in the state of being semicured can be heat-curedby being further heated by a heating oven, for example, at a temperatureof 170 to 250° C., preferably 185 to 230° C., for 60 to 150 min.

The thickness of the resin film according to the present embodiment isnot especially limited, but it is preferable that the thickness be 1 to200 μm; being 2 to 180 μm is more preferable; and being 3 to 150 μm isstill more preferable. When the thickness of the resin film is made tobe in the above range, there are easily satisfied simultaneously boththe thickness reduction and the good high-frequency characteristics of aprinted wiring board obtained by using the resin film according to thepresent embodiment.

The support base material is not especially limited, but examplesthereof include glasses, metal foils and PET films. When the resin filmhas the support base material, the storage property and thehandleability in production use of a printed wiring board are likely tobecome good. That is, the resin film according to the present embodimentcan take a form of a support with a resin layer which has a resin layercontaining the resin composition of the present embodiment and thesupport base material, and the resin layer may be peeled off the supportbase material when the resin film is used.

In conventional resin films for printed wiring boards, in the case whereno glass cloth or the like is blended in their resin compositions, it islikely that the handleability of the resin films becomes worse and thestrength cannot also be sufficiently held. By contrast, the resin filmof the present embodiment, particularly since being formed from theflexible resin composition having the (A) component, even without glasscloth or the like, there is made a resin film thin and excellent inhandleability (tackiness, cracking, powder dropping and the like).Further the resin film of the present embodiment is sufficiently high inthe peel strength to a low-profile foil or the like. Hence, alow-profile foil can be used without any problem, and there can furtherbe provided a printed wiring board sufficiently reduced in thetransmission loss. Further the resin film of the present embodiment cansimultaneously attain excellent appearance and multilayeringmoldability, and is excellent also in the heat resistance and themoisture resistance.

[Prepreg]

The prepreg of the present embodiment can be obtained, for example, bycoating the resin composition of the present embodiment on a fiber basematerial being a reinforcing base material and drying the coated resincomposition. Further the prepreg of the present embodiment may beobtained by impregnating the fiber base material with the resincomposition of the present embodiment, and thereafter drying theimpregnated resin composition. Specifically, the prepreg in which theresin composition is semicured is obtained by drying the fiber basematerial on which the resin composition adheres in a drying oven usuallyat a temperature of 80 to 200° C. for 1 to 30 min. With respect to theamount of the resin composition adhering on the fiber base material,from the viewpoint of the good moldability, it is preferable that theresin composition be coated or impregnated so that the resin contentratio in the prepreg after the drying becomes 30 to 90% by mass.

The reinforcing base material of the prepreg is not especially limited,but a sheet-form fiber base material is preferable. As the sheet-formfiber base material, there are used, for example, well-known ones beingused for various types of laminates for electric insulating materials.Examples of materials therefor include inorganic fibers of E glass, NEglass, S glass, Q glass or the like; and organic fibers of polyimide,polyester, tetrafluoroethylene or the like. As the sheet-form fiber basematerial, there can be used ones having a shape of woven fabric,nonwoven fabric, chopped strand mat or the like. Further the thicknessof the sheet-form fiber base material is not especially limited, and thesheet-form fiber base materials of, for example, 0.02 to 0.5 mm can beused. Further as the sheet-form fiber base material, ones having beensubjected to a surface treatment with a coupling agent or the like, orhaving been subjected to a mechanical fiber opening treatment arepreferable from the viewpoint of the impregnatability of the resincomposition, and the heat resistance, hygroscopic resistance andprocessability of a laminate when the fiber base material is made intothe laminate.

[Laminate]

According to the present embodiment, there can be provided a laminatehaving a resin layer containing a cured substance of the above-mentionedresin composition, and a conductor layer. For example, a metal-cladlaminate can be produced by using the resin film or the prepreg. Themetal-clad laminate obtained by using the resin film or the prepreg,since having a high solder heat resistance capable of withstanding asolder connection step in the mounting, and being excellent also in thehygroscopic resistance, becomes one suitable for outdoor applications.

A production method of the metal-clad laminate is not limited, but ametal-clad laminate having a metal foil on at least one surface of theresin layer or the prepreg to become an insulating layer can beobtained, for example, by disposing the metal foil to become a conductorlayer on at least one surface of one sheet or a plurality of stackedsheets of the resin film or the prepreg according to the presentembodiment, and heating and pressing the resultant, for example, at atemperature of 170 to 250° C., preferably 185 to 230° C., and at apressure of 0.5 to 5.0 MPa for 60 to 150 min. The heating and pressingcan be carried out, for example, under the condition of a degree ofvacuum of 10 kPa or lower, preferably 5 kPa or lower, and from theviewpoint of enhancing the efficiency, it is preferable that the heatingand pressing be carried out in vacuum. It is preferable that the heatingand pressing be carried out for 30 min from the starting time to untilthe molding-finishing time therefrom.

[Multilayer Printed Wiring Board]

According to the present embodiment, there can be provided a multilayerprinted wiring board having a resin layer containing a cured substanceof the above-mentioned resin composition, and circuit layers. The upperlimit value of the number of circuit layers is not especially limited,and may be 3 layers to 20 layers. A multilayer printed wiring board canalso be produced, for example, by using the above-mentioned resin film,prepreg or metal-clad laminate.

A production method of a multilayer printed wiring board is notespecially limited, but a multilayer printed wiring board can beproduced, for example, by first disposing the resin film on one surfaceor both surfaces of a core substrate having been subjected to a circuitformation processing or disposing the resin film between a plurality ofcore substrates, subjecting the resultant to pressing and heatinglamination molding or pressing and heating press molding to adhere theeach layer, and thereafter subjecting the resultant to a circuitformation processing by laser boring processing, drill boringprocessing, metal plating processing, metal etching processing or thelike. In the case where the resin film has a support base material, thesupport base material can be peeled off in advance before the resin filmis disposed on a core substrate or between core substrates, or be peeledoff after the resin layer is laminated on the core substrate.

A production method of a multilayer printed wiring board using the resinfilm according to the present embodiment will be described by way ofFIG. 1. FIG. 1 is a diagram schematically illustrating production stepsof the multilayer printed wiring board according to the presentembodiment. The production method of the multilayer printed wiring boardaccording to the present embodiment comprises (a) a step (hereinafter,referred to as “step (a)”) of laminating a resin film on an inner layercircuit board to form a resin layer, (b) a step (hereinafter, referredto as “step (b)”) of heating and pressing the resin layer to cure theresin layer, and (c) a step (hereinafter, referred to as “step (c)”) offorming an antenna circuit layer on the cured resin layer.

As illustrated in (a) of FIG. 1, a resin film 12 according to thepresent embodiment is laminated on an inner layer circuit board 11 tothereby form a resin layer consisting of the resin film 12 in the step(a).

A lamination method is not especially limited, but examples thereofinclude a method of laminating by using a multi-daylight press, a vacuumpress, an atmospheric laminator or a laminator which performs heatingand pressing under vacuum, and preferable is a method using thelaminator which performs heating and pressing under vacuum. Thereby,even if the inner layer circuit board 11 has fine wiring circuits on itssurface, spaces between the circuits can be embedded in the resinwithout producing voids. The lamination condition is not especiallylimited, but it is preferable that the lamination be carried out at apressure bonding temperature of 70 to 130° C. and a pressure bondingpressure of 1 to 11 kgf/cm², and under reduced pressure or under vacuum.The lamination may be carried out in a batch system or a continuoussystem using rolls.

The inner layer circuit board 11 can use, without being especiallylimited, a glass epoxy substrate, a metal substrate, a polyestersubstrate, a polyimide substrate, a BT resin substrate, a thermosettingpolyphenylene ether substrate, or the like. The circuit surface on thesurface side of the inner layer circuit board 11 on which the resin filmis to be laminated may be previously subjected to a rougheningtreatment.

The number of circuit layers of the inner layer circuit board 11 is notlimited. FIG. 1 illustrates an inner layer circuit board having 6layers, but the number thereof is not limited to this number of layers;for example, in the case of fabricating a printed wiring board for amillimeter-wave radar, the number thereof can optionally be selectedfrom 2 layers to 20 layers or so according to the design concerned. Themultilayer printed wiring board of the present embodiment can be appliedto fabrication of a millimeter-wave radar. That is, there can befabricated a printed wiring board for a millimeter-wave radar which hasa resin layer containing a cured substance of the resin film accordingto the present embodiment, and a circuit layer.

In the case where an antenna circuit layer 14 described later is formedon a resin layer 12 a by etching, a metal foil 13 may further belaminated on the resin film 12 to form a metal layer 13 a. Examples ofthe metal foil include copper, aluminum, nickel and zinc, and from theviewpoint of the conductivity, copper is preferable. The metal foil maybe an alloy, and examples of copper alloys include high-purity copperalloys in which a small amount of beryllium or cadmium is added. It ispreferable that the thickness of the metal foil be 3 to 200 μm; andbeing 5 to 70 μm is more preferable.

As illustrated in (b) of FIG. 1, the inner layer circuit board 11 andthe resin layer 12 a laminated in the step (a) are heated and pressed tobe heat-cured in the step (b). The condition is not especially limited,but it is preferable that the condition be in the ranges of atemperature of 100° C. to 250° C., a pressure of 0.2 to 10 MPa and atime of 30 to 120 min; and being 150° C. to 220° C. is more preferable.

As illustrated in (c) of FIG. 1, the antenna circuit layer 14 is formedon the resin layer 12 a in the step (c). A formation method of theantenna circuit layer 14 is not especially limited, and the antennacircuit layer 14 may be formed, for example, by an etching process suchas a subtractive process or a semi-additive process.

The subtractive process is a process of forming a desired circuit byforming an etching resist layer having a shape corresponding to adesired pattern shape on the metal layer 13 a, and in a developingprocess thereafter, dissolving and removing the metal layer in portionswhere the resist is removed by using a chemical. For example, a copperchloride solution or an iron chloride solution can be used as thechemical.

The semi-additive process is a process of forming a desired circuitlayer by forming a metal film on the surface of the resin layer 12 a byan electroless plating method, forming a plating resist layer having ashape corresponding to a desired pattern on the metal film, then forminga metal layer by an electroplating method, and thereafter removing anunnecessary electrolessly plated layer by using a chemical or the like.

Further in the resin layer 12 a, as required, holes such as a via hole15 may be formed. A formation method of the hole is not limited, butthere can be applied an NC drill, a carbon dioxide laser, a UV laser, aYAG laser, a plasma or the like.

Here, the inner layer circuit board 11 may also be produced by steps (p)to (r) illustrated in FIG. 2. FIG. 2 is a diagram schematicallyillustrating production steps of an inner layer circuit board. That is,the production method of the multilayer printed wiring board accordingto the present embodiment may comprise a step (p), a step (q), a step(r), the step (a), the step (b) and the step (c). Hereinafter, the steps(p) to (r) will be described.

First, as illustrated in (p) of FIG. 2, core substrates 41 and prepregs42 are laminated in the step (p). As the core substrate, there can beused, for example, a glass epoxy substrate, a metal substrate, apolyester substrate, a polyimide substrate, a BT resin substrate, or athermosetting polyphenylene ether substrate. As the prepreg, there canbe used, for example, “GWA-900G”, “GWA-910G”, “GHA-679G”, “GHA-679G(S)”,“GZA-71G” or “GEA-75G” (all, trade names), manufactured by HitachiChemical Co., Ltd.

Next, as illustrated in (q) of FIG. 2, a laminated body obtained in thestep (p) of the core substrates 41 and the prepregs 42 is heated andpressed in the step (q). The heating temperature is not especiallylimited, but it is preferable to be 120 to 230° C.; and being 150 to210° C. is more preferable. Further the pressing pressure is notespecially limited, but it is preferable to be 1 to 5 MPa; and being 2to 4 MPa is more preferable. The heating time is not especially limited,but it is preferable to be 30 to 120 min. Thereby, there can be obtainedan inner layer circuit board excellent in the dielectriccharacteristics, and the mechanical and electrical connectionreliability in a high-temperature high-humidity.

Further as illustrated in (r) of FIG. 2, as required, a through hole 43is formed in the inner layer circuit board in the step (r). A formationmethod of the through hole 43 is not especially limited, and may be thesame as the above-mentioned step of forming the antenna circuit layer,or may use a known method.

By the above steps, there can be produced the multilayer printed wiringboard of the present embodiment. The steps (a) to (c) may further berepeated by using the printed wiring board produced in the above stepsas an inner layer circuit board.

FIG. 3 is a diagram schematically illustrating production steps, of amultilayer printed wiring board, using the multilayer printed wiringboard produced by the steps illustrated in FIG. 1 as an inner layercircuit board. FIG. 3(a), FIG. 3(b) and FIG. 3(c) correspond to FIG.1(a), FIG. 1(b) and FIG. 1(c), respectively.

Specifically, (a) of FIG. 3 illustrates a step of laminating a resinfilm 22 on an inner layer circuit board 21 to form a resin layer 22 a,and as required, laminating a metal foil 23 on the resin film 22 to forma metal layer 23 a. (b) of FIG. 3 illustrates a step of heating andpressing the resin layer 22 a to cure the resin layer 22 a; and (c) ofFIG. 3 illustrates a step of forming an antenna circuit layer 24 on thecured resin layer.

In FIG. 1 and FIG. 3, the number of the resin layers laminated on theinner layer circuit board for the purpose of forming an antenna circuitpattern and the like is made to be one layer or two layers, but thenumber thereof is not limited thereto; and the number of layers may bemade to be 3 or more layers according to the antenna circuit design. Bymaking an antenna circuit layer to be multilayer, it becomes easy todesign antennas having wideband characteristics and antennas exhibitinglittle angular variation (beam tiltless) in antenna radiation patternsin the use frequency band.

The production method of the multilayer printed wiring board accordingto the present embodiment, since forming the resin layer by using theresin film containing the (A) component and the (B) component, canfabricate the laminated body without providing an adhesive layer exceptfor providing the layer excellent in the high-frequency characteristics.Thereby, the simplification of the steps can be achieved and the effectof further improving the high-frequency characteristics can be attained.

The resin composition, the resin film, the prepreg, the laminate, andthe multilayer printed wiring board according to the present embodimentas described above can suitably be used for electronic devices handlinghigh-frequency signals of 1 GHz or higher, particularly electronicdevices handling high-frequency signals of 10 GHz or higher.

Hitherto, the preferred embodiments according to the present inventionhave been described, but are taken as examples to describe the presentinvention; and there is no tenor of limiting the scope of the presentinvention to the embodiments. The present invention can be carried outin various modes different from the above embodiments without departingfrom its gist.

EXAMPLES

Hereinafter, the present invention will be described in more detailbased on Examples and Comparative Examples. However, the presentinvention is not limited to the following Examples.

[Preparation of Resin Compositions]

Various resin compositions were prepared according to the followingprocedure. The amounts (parts by mass) of each raw material used for thepreparation of resin compositions of Examples 1 to 12 and ComparativeExamples 1 to 5 are collectively shown in Tables 1 and 2.

Each component indicated in Table 1 or Table 2 was charged in a 300-mLfour-necked flask equipped with a thermometer, a reflux cooling tube anda stirring apparatus, stirred at 25° C. for 1 hour, and thereafterfiltered with a #200 nylon mesh (opening: 75 μm) to thereby obtain resincompositions.

Here, the abbreviations and the like of each material in Table 1 andTable 2 are as follows.

(1) (A) Component

BMI-3000 [Mw: about 3000, manufactured by Designer Molecules Inc., tradename]

BMI-5000 [Mw: about 5000, manufactured by Designer Molecules Inc., tradename]

(2) (B) Component

Perbutyl P [di(2-t-butylperoxyisopropyl)benzene, one-minute half-lifetemperature: 175° C., one-hour half-life temperature: 138° C.,manufactured by NOF Corp., trade name]

Percumyl D [dicumyl peroxide, one-minute half-life temperature: 175° C.,one-hour half-life temperature: 136° C., manufactured by NOF Corp.,trade name]

Perhexyne 25B [2,5-dimethyl-2,5-di(t-butylperoxy)hexane-3, one-minutehalf-life temperature: 180° C., one-hour half-life temperature: 138° C.,manufactured by NOF Corp., trade name]

Perbutyl A [t-butyl peroxyacetate, one-minute half-life temperature:160° C., one-hour half-life temperature: 121° C., manufactured by NOFCorp., trade name]

Perbutyl 1 [t-butyl peroxyisopropylmonocarbonate, one-minute half-lifetemperature: 159° C., one-hour half-life temperature: 118° C.,manufactured by NOF Corp., trade name]

G-8009L [isocyanate-masked imidazole (addition reaction product of ahexamethylene diisocyanate resin and 2-ethyl-4-methylimidazole),manufactured by DKS Co., Ltd., trade name]

TPP-MK [a tetraphenylphosphonium, manufactured by Hokko Sangyo Co.,Ltd., trade name]

(3) (B)′ component (a catalyst different from the (B) component) Zincnaphthenate [manufactured by Tokyo Chemical Industry Co., Ltd.]

(4) (C) Component

BMI-1000 [bis(4-maleimidophenyl)methane, manufactured by Daiwa KaseiIndustrial Co., Ltd., trade name]

BMI-4000 [2,2-bis(4-(4-maleimidophenoxy)phenyl)propane, manufactured byDaiwa Kasei Industrial Co., Ltd., trade name]

(5) Diamine

Bisaniline M [1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, manufacturedby Mitsui Fine Chemicals, Inc., trade name]

(6) Inorganic Filler

A silica slurry [a spherical fused silica, surface treatment: aphenylaminosilane coupling agent (10% by mass/total solid content in theslurry), disperse medium: methyl isobutyl ketone (MIBK), solid contentconcentration: 70% by mass, average particle diameter: 0.5 μm, density:2.2 g/cm³, manufactured by Admatex Co., Ltd., trade name: “SC-2050KNK” ]

(7) Solvent

Toluene [manufactured by Kanto Chemical Co., Inc.]

TABLE 1 Examples 1 2 3 4 5 6 7 8 9 10 11 12 (A) BMI-3000 100 100 100 100100 90 — 100 100 100 90 90 Component BMI-5000 — — — — — — 90 — — — — —Perbutyl P — —  2 — — — — — —  2  2 — Percumyl D —  2 — — — —  2 — — — —— (B) Perhexyne  2 — — — —  2 — — — — — — Component 25B Perbutyl A — — — 2 — — — — — — — — Perbutyl I — — — —  2 — — — — — — — G8009L — — — — —— —  2 —  1 — — TPP-MK — — — — — — — —  2 — —  2 (C) BMI-1000 — — — — —— 10 — — — — — Component BMI-4000 — — — — — 10 — — — —  8  8 DiamineBisaniline M — — — — — — — — — —  2  2 Silica Slurry 400 400 400 400 400400 400 400 400 400 400 400 * the number in ( ) indicates (120) (120)(120) (120) (120) (120) (120) (120) (120) (120) (120) (120) the amountof solvent Solvent Toluene   43.7   43.7   43.7   43.7   43.7   43.7  43.7   43.7   43.7   43.7   43.7   43.7

TABLE 2 Comparative Examples 1 2 3 4 5 (A) BMI-3000 — — — 100 100 Compo-BMI-5000 — — — — — nent (B) Perbutyl P — —  2 — — Compo- G8009L  2  2 —— — nent (B)′ Zinc — — —  2 — Compo- Naphthe- nent nate (C) BMI-1000 100— — — — Compo- BMI-4000 — 100 80 — — nent Diamine Bisaniline — — 20 — —M Silica Slurry 400 400 400 400 400 * the number in ( ) (120) (120)(120) (120) (120) indicates the amount of solvent Solvent Toluene   43.7  43.7   43.7   43.7   43.7

Here, presumed structures of the compounds (BMI-3000 and BMI-5000) usedas the (A) component are as the following formula (XII-3)

[Fabrication of Resin Films in a Semicured State]

The resin compositions obtained in Examples 1 to 12 and ComparativeExamples 1 to 5 were each coated on a PET film (manufactured by TeijinLtd., trade name: “G2-38”) of 38 μm in thickness as a support basematerial by using a comma coater, and dried at a drying temperature of130° C. for 10 min to thereby fabricate semicured resin films with a PETfilm, which had a resin layer in a semicured state. The thickness of thesemicured resin films (resin layers) was 50 μm.

[Evaluation of the Resin Films]

There were evaluated the appearance and the handleability of thesemicured resin films of the Examples 1 to 12 and the ComparativeExamples 1 to 5. The evaluation results are shown in Table 3 and Table4.

The appearance was visually evaluated according to the followingcriteria.

◯: there were no unevenness, no streaks and the like on the surface ofthe semicured resin film.

×: there were unevenness, streaks and the like in an impracticable stateon the surface of the semicured resin film, and the surface smoothnesswas poor.

The handleability was evaluated visually and tactually according to thefollowing criteria.

(1) Presence/absence of tackiness on the surface at 25° C.

(2) Presence/absence of resin cracking or powder dropping when being cutby a cutter knife.

◯: Both of the above (1) and (2) were absent.

×: At least either one of the above (1) and (2) was present.

[Multilayer Printed Wiring Boards]

Multilayer printed wiring boards were fabricated by the followingprocedure by using the above-mentioned semicured resin films with a PETfilm.

A glass fabric base epoxy resin copper-clad laminate having circuitpatterns formed therein was used as an inner layer circuit board; onesheet of the semicured resin film obtained by peeling the PET film offwas placed on each of both surfaces of the inner layer circuit board; anelectrodeposited copper foil (manufactured by Nippon Denkai, Ltd., tradename: “YGP-12”) of 12 μm in thickness was disposed on each of thesheets; thereafter, end plates were placed thereon; and the resultantwas subjected to heating and pressing molding under the pressingcondition of 200° C./3.0 MPa/70 min to thereby fabricate a 4-layeredprinted wiring board.

Then, the copper foils of the outermost layers of the fabricated4-layered printed wiring board were etched to evaluate the circuitembeddability (multilayering moldability). The multilayering moldabilitywas visually evaluated according to the following criteria.

◯: No voids nor blurs were present on the circuits.

×: More or less voids and blurs were present.

[Double-Sided Metal-Clad Cured Resin Films]

After two sheets of the resin film obtained by peeling the PET film offfrom the above semicured resin film with the PET film were stacked; alow-profile copper foil (M-surface Rz: 3 μm, manufactured by FurukawaElectric Co., Ltd., trade name: “F3-WS”) of 18 μm in thickness wasdisposed on each of both surfaces of the stacked two sheets so that theroughened surface (M-surface) contacted therewith; an end plate wasplaced on each of the copper foils; and the resultant was subjected toheating and pressing molding under the pressing condition of 200° C./3.0MPa/70 min to thereby fabricate a double-sided metal-clad cured resinfilm (thickness: 0.1 mm).

For the above double-sided metal-clad cured resin film, there wereevaluated the handleability (bending resistance), the dielectriccharacteristics, the copper foil peel strength, the solder heatresistance and the thermal expansion characteristics. The evaluationresults are shown in Table 3 and Table 4. Methods for evaluating thecharacteristics of the double-sided metal-clad cured resin film were asfollows.

[Bending Resistance]

The bending resistance was evaluated according to the following criteriaby bending, by 180°, the double-sided metal-clad cured resin film whoseouter layer copper foils had been etched.

◯: No breaking nor cracking were generated on bending.

×: More or less breaking and cracking were generated on bending.

[Dielectric Characteristics]

The relative dielectric constant and the dielectric loss tangent beingthe dielectric characteristics were measured by a cavity resonatorperturbation method, by using a test piece prepared by etching the outerlayer copper foils of the double-sided metal-clad cured resin film andcutting the resultant into 60 mm in length, 2 mm in width and about 1 mmin thickness. A measuring device used was a vector network analyzerE8364B, manufactured by Agilent Technologies, Inc.; cavity resonatorsused were CP129 (10-GHz band resonator) and CP137 (20-GHz bandresonator), manufactured by Kanto Electronics Application andDevelopment Inc.; and the measurement program used was CPMA-V2. Thecondition was set at frequencies of 10 GHz and at a measurementtemperature of 25° C.

[Thermal Expansion Coefficient (CTE)]

For the evaluation of the thermal expansion coefficient (in the filmthickness direction), a test piece was prepared by etching the copperfoils of both sides of the double-sided metal-clad cured resin film andcutting the resultant into 50 mm square; and the thermal expansioncoefficient of the test piece was measured by a thermomechanicalanalyzer TMA (manufactured by TA Instruments Inc., Q400) (temperaturerange: 30 to 150° C., load: 5 g) according to the IPC standard(IPC-TM-650 2.4.24).

[Copper Foil Peel Strength]

The copper foil peel strength of the double-sided metal-clad cured resinfilm was measured according to the standard for test methods ofcopper-clad laminates, JIS-C-6481.

[Solder Heat Resistance]

For the evaluation of the solder heat resistance, test pieces wereprepared by etching the copper foil of one side of the double-sidedmetal-clad cured resin film and cutting the resultant into 50 mm square;the test pieces in the normal condition and test pieces having beentreated for predetermined times (1, 3 and 5 hours) in a pressure cookertest (PCT) apparatus (condition: 121° C., 2.2 atm) were made to flow ona molten solder at 288° C. for 20 sec; and the appearance of sheets ofthe cured resin films different in the treatment time was visuallyevaluated according to the following criteria. The evaluation wascarried out by using three sheets of the cured resin film for the sametreatment time; and the number of sheets exhibiting “◯” in the followingcriteria is shown in Table 3 and Table 4. Here, in Table 3 and Table 4,the test piece having been treated for 1 hour is represented as PCT-1h;the test piece having been treated for 3 hours is represented as PCT-3h;and the test piece having been treated for 5 hours is represented asPCT-5h.

◯: No generation of blistering or measling in the film interior andbetween the film and the copper foil was recognized.

×: Generation of blistering or measling in the film interior and betweenthe film and the copper foil was observed.

TABLE 3 Examples 1 2 3 4 5 6 7 8 9 10 11 12 Semicured Appearance ◯ ◯ ◯ ◯◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Resin Film Handleability ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯Characteristics Multilayering ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ MoldabilityBending Resistance ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Relative 10 GHz 2.98 2.982.98 3.00 3.02 3.06 3.00 3.00 3.00 3.06 3.00 3.00 Dielectric ConstantDielectric 10 GHz 0.0016 0.0016 0.0016 0.0017 0.0017 0.0016 0.00170.0017 0.0017 0.0016 0.0017 0.0017 Loss Tangent CTE (ppm/° C.) 85 92 8898 99 35 41 1.03 1.01 60 41 56 Copper Foil Peel Strength 0.87 0.85 0.850.80 0.81 0.85 0.82 0.79 0.82 0.85 0.82 0.82 (kN/m) Solder Heat Normal 33 3 3 3 3 3 3 3 3 3 3 Resistance Condition PCT-1 h 3 3 3 3 3 3 3 3 3 3 33 PCT-3 h 3 3 3 3 2 3 3 2 1 3 3 3 PCT-5 h 3 3 3 1 1 3 3 1 0 3 3 1

TABLE 4 Comparative Examples 1 2 3 4 5 Semicured Appearance ◯ ◯ ◯ ◯ ◯Resin Film Handleability X X X ◯ ◯ Characteristics Multilayering ◯ ◯ ◯ ◯◯ Moldability Bending Resistance ◯ ◯ ◯ ◯ ◯ Relative Dielectric 10 GHz3.11 3.10 3.16 2.98 2.98 Constant Dielectric 10 GHz 0.0100 0.0080 0.01200.0018 0.0018 Loss Tangent CTE (ppm/° C.) 16 18 18 120 160 Copper FoilPeel Strength (kN/m) 0.45 0.55 0.71 0.85 0.85 Solder Heat Normal 3 3 3 30 Resistance Condition PCT-1 h 3 3 3 0 0 PCT-3 h 3 3 3 0 0 PCT-5 h 3 3 30 0

As is clear from the results shown in Table 3, it was confirmed that theresin films made by using the resin compositions of Examples 1 to 12were better in the high-frequency characteristics, the adhesiveness toconductors and the handleability (tackiness, cracking, powder droppingand the like) as well than Comparative Examples 1 to 3, which containedno (A) component, and were better in the solder heat resistance andexhibited a lower thermal expansion property than Comparative Examples 4and 5, which contained no (B) component. Further it was confirmed thatparticularly the resin compositions of Examples 1 to 3, which usedorganic peroxides higher in the one-minute half-life temperature and theone-hour half-life temperature, were better in the heat resistance.

REFERENCE SIGNS LIST

11, 21: inner layer circuit board, 12, 22: resin film, 12 a, 22 a: resinlayer, 13, 23: metal foil, 13 a, 23 a: metal layer, 14, 24: antennacircuit layer, 15: via hole, 42: prepreg, 41: core substrate, and 43:through-hole.

The invention claimed is:
 1. A resin composition comprising: a maleimidecompound (A) having a maleimide group, a saturated or unsaturateddivalent hydrocarbon group and a divalent group having at least twoimido bonds and being represented by the following formula

wherein R and each independently represent a divalent organic group andn represents an integer of 1 to 10; a catalyst (B) comprising at leastone selected from the group consisting of an imidazole compound, aphosphorus compound, an azo compound and an organic peroxide, wherein acontent of the catalyst is 0.1 to 10 parts by mass with respect to 100parts by mass of the maleimide compound (A); a diamine compound or anaromatic maleimide compound (C) different from the maleimide compound(A),wherein, if the aromatic maleimide compound (C) different from themaleimide compound (A) has the above formula, at least one of R and Q isdifferent than R or Q in the maleimide compound (A); and an inorganicfiller.
 2. The resin composition according to claim 1, wherein thecatalyst comprises an organic peroxide.
 3. The resin compositionaccording to claim 1, wherein a one-hour half-life temperature of theorganic peroxide is 110 to 250° C.
 4. The resin composition according toclaim 1, wherein the number of carbon atoms of the hydrocarbon group is8 to
 100. 5. The resin composition according to claim 1, wherein thehydrocarbon group is a group represented by the following formula (II):

wherein in the formula (II), R₂ and R₃ each independently represent analkylene group having 4 to 50 carbon atoms: R₄ represents an, alkylgroup having 4 to 50 carbon atoms; and R₅ represents an alkyl grouphaving 2 to 50 carbon atoms.
 6. A resin film made by using the resincomposition according to claim
 1. 7. A laminate comprising: a resinlayer comprising a cured substance of the resin composition according toclaim 1; and a conductor layer.
 8. A multilayer printed wiring boardcomprising: a resin layer comprising a cured substance of the resincomposition according to claim 1; and circuit layers.
 9. A method forproducing a multilayer printed wiring board, comprising: a step oflaminating the resin film according to claim 6 on an inner layer circuitboard to form a resin layer; a step of heating and pressing the resinlayer to cure the resin layer; and a step of forming a circuit layer onthe cured resin layer.
 10. The resin composition according to claim 1,wherein the content of the catalyst is 1 to 5 parts by mass with respectto 100 parts by mass of the maleimide compound.
 11. The resincomposition according to claim 1, wherein the content of the catalyst is1.5 to 5 parts by mass with respect to 100 parts by mass of themaleimide compound.
 12. The resin composition according to claim 1,wherein the inorganic filler comprises at least one selected from thegroup consisting of silica, alumina, titanium oxide, mica, beryllia,barium titanate, potassium titanate, strontium titanate, calciumtitanate, aluminum carbonate, magnesium hydroxide, aluminum hydroxide,aluminum silicate, calcium carbonate, calcium silicate, magnesiumsilicate, silicon nitride, boron nitride, calcined clay, talc, aluminumborate and silicon carbide.
 13. The resin composition according to claim12, wherein the inorganic filler has a particle diameter of 0.01 to 20μm.
 14. The resin composition according to claim 12, wherein theinorganic filler has a particle diameter of 0.1 to 10 μm.
 15. The resincomposition according to claim 1, wherein a content of the inorganicfiller is 3 to 75% by volume with respect to a total volume of a solidcontent in the resin composition.
 16. The resin composition according toclaim 1, wherein a content of the inorganic filler is 5 to 70% by volumewith respect to a total volume of a solid content in the resincomposition.
 17. The resin composition according to claim 1, wherein acontent of the inorganic filler is 5 to 90% by mass with respect to atotal volume of a solid content in the resin composition.
 18. The resincomposition according to claim 1, wherein a content of the inorganicfiller is 10 to 80% by mass with respect to a total volume of a solidcontent in the resin composition.
 19. The resin composition according toclaim 1, wherein the catalyst (B) comprises at least one selected fromthe group consisting of methylimidazole, phenylimidazole, anisocyanate-masked imidazole, an organophosphine, complexes oforganophosphines and organoborons, adducts of tertiary phosphine withquinones, 2,2′-azobis-isobutyronitrile,2,2′-azobis-2-methylbutyronitrile,1,1′-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2′-azobisisobutyrate,1,1′-azobis-(1-acetoxy-1-phenylethane), dicumyl peroxide, dibenzoylperoxide, 2-butanone peroxide, tert-butyl perbenzoate, di-tert-butylperoxide, 2,5-bis (tert-butylperoxy)-2,5-dimethylhexane,bis(tert-butylperoxyisopropyl)benzene, tert-butyl hydroperoxide,di(4-methylbenzoyl) peroxide, di(3-methylbenzoyl) peroxide, dibenzoylperoxide, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, dilauroylperoxide, di(3,5,5-trimethylhexanoyl) peroxide and tert-butylperoxypivalate.
 20. The resin composition according to claim 1, whereinthe catalyst comprises an organic peroxide having a one-hour half-lifetemperature of 110 to 250° C.